1. Field of the Invention
The present invention relates to susceptors made of ceramic material for heating objects to be placed and processed on placing faces thereof in semiconductor-producing apparatuses.
2. Related Statement
Ceramic heaters in which a resistance heat-generating element is buried in a susceptor made of a ceramic material such as silicon nitride have been used for heating semiconductor wafers in semiconductor-producing apparatuses. Further, heaters in which a high frequency plasma-generating electrode is buried have been also used in the semiconductor-producing apparatuses. In such an apparatus, an object to be processed, such as a silicon wafer or a substrate for a liquid crystal, is placed on a susceptor, and the processed object is lifted with lift pins to release the supporting of the object after processing, and then conveyed.
The inventors discovered that when the wafer was placed on the susceptor, was subjected to a given processing under heating in a plasma environment, and was to be lifted with the lift pins to release the supporting of the object, the wafer might be positionally deviated by a few or several millimeters on the placing face of the susceptor through the wafer being absorbed onto the placing face of the susceptor.
It is therefore an object of the present invention to prevent positional deviation of a wafer through a phenomenon that the wafer is absorbed onto the placing face of the susceptor when the wafer is supported and processed under heating on the susceptor and the wafer is released from being supported.
The present invention relates to the susceptor made of a ceramic material for placing and heating an object to be processing, on a placing face thereof in a semiconductor-producing apparatus, said susceptor comprising a surface layer having said placing face, and a supporting layer integrated with said surface layer, a volume resistivity of the surface layer being lower than that of the supporting layer.
The present inventors succeeded in preventing the positional deviation of the object due to the absorbing phenomenon of the object onto the placing face of the susceptor at a time of releasing the supporting of the object thereon by the provision of the surface layer having a lower volume resistivity on the ceramic susceptor.
The present invention can be favorably applied particularly to placing and heating the object to be processed in a plasma environment.
These and other objects, features and advantages of the invention will be appreciated upon reading of the following description of the drawings, with the understanding that some modifications, variations and changes of the invention could be easily made by the skilled person in the art to which the invention pertains.